278 



The shape of Erylus euastruin (O. S.) is irregalar with one or 

 more bluntly conical processus on which a single proct is visible. 

 The surface is uneven , smooth ; no spicules project beyond the 

 surface. Stomas are scattered over the surface. The colour is 

 purplish browu. 



The section througb the living animal at right angles through 

 the proct shows a yellowish parenchyme and a thin dark cortex. 

 One or two wide main excurrent canals open into the proct. The 

 stomas are the openings of chones ; no distinction can be made 

 between endo- and ectochone, and nothing can be seen of a 

 sphincter. Under the cortex rudimentary crypts can be distin- 

 guished. From these crypts rather wide canals start which become 

 narrower and ramify, till they end in distinct prosodi. The 

 aphodi are shorter and wider thau the prosodi; the flagellated 

 chambers are ellipsoid. 



The skeleton of the cortex consists of about six layers of sterr- 

 asters packed closely together. The dermal part of the cortex 

 is strengthened by microxeas , and in addition to these a few 

 minute spherasters occur. The parenchymal skeleton shows a 

 similar arrangement as in Caminus , and consists chiefly of oxeas. 

 Strongyles are mixed with these and just beneath the cortex a 

 few orthotriaenes occur. Between these megascleres there are 

 abundantly oxyasters and minute spherasters. 



Spicules. Oxea. They vary considerably in length; the shape 

 is generally somewhat fusiform and not quite straight. The ex- 

 tremities are as a rule rather blunt. With a low power this is 

 hardly to be seen ; with a high power it becomes however clear that 

 they are in fact blunt-ended oxeas; some of them are sharp-pointed. 



Strongyle. Not as frequent as the oxeas, smaller thau these, 

 eylindrical or slightly fusiform. 



Orthotriaene. Rhabdome only a little longer than the cladi, 

 straight or slightly curved, sharply pointed. Not frequent ; occuring 

 especially close under the cortex. 



Sterraster. Disc-like ; the longest diameter about six time the 

 thickness; surface granulated; outline irregular. 



